Implications for Detection and Delineation of Forest Insect Infestations

The branch-level spectral data for both tree species infested with their specific invasive adelgids were both consistent and in general agreement with the shoot-level spectral changes of balsam fir under various stresses that were measured under laboratory conditions (Luther and Carroll 1999). The measurements were also in general agreement with the results of Pontius and others (2005) who examined hemlock woolly adelgid at the landscape level. Therefore, the spectral changes that occur with stress are measurable at several scales. The combined results of these studies suggest that spectral data may aide in developing a tool for previsual detection and monitoring of forest decline associated with these adelgid species. However, limitations do exist. One of the primary limitations may be the ability to separate different stressing agents or factors.